title: Fibroblast growth factor-2 induced by enriched environment enhances angiogenesis and motor function in chronic hypoxic-ischemic brain injury.
abstract: This study aimed to investigate the effects of enriched environment (EE) on promoting angiogenesis and neurobehavioral function in an animal model of chronic hypoxic-ischemic (HI) brain injury. HI brain damage was induced in seven day-old CD-1® mice by unilateral carotid artery ligation and exposure to hypoxia (8% O2 for 90 min). At six weeks of age, the mice were randomly assigned to either EE or standard cages (SC) for two months. Rotarod, forelimb-use asymmetry, and grip strength tests were performed to evaluate neurobehavioral function. In order to identify angiogenic growth factors regulated by EE, an array-based multiplex ELISA assay was used to measure the expression in frontal cortex, striatum, and cerebellum. Among the growth factors, the expression of fibroblast growth factor-2 (FGF-2) was confirmed using western blotting. Platelet endothelial cell adhesion molecule-1 (PECAM-1) and α-smooth muscle actin (α-SMA) were also evaluated using immunohistochemistry. As a result, mice exposed to EE showed significant improvements in rotarod and ladder walking performances compared to SC controls. The level of FGF-2 was significantly higher in the frontal cortex of EE mice at 8 weeks after treatment in multiplex ELISA and western blot. On the other hand, FGF-2 in the striatum significantly increased at 2 weeks after exposure to EE earlier than in the frontal cortex. Expression of activin A was similarly upregulated as FGF-2 expression pattern. Particularly, all animals treated with FGF-2 neutralizing antibody abolished the beneficial effect of EE on motor performance relative to mice not given anti-FGF-2. Immunohistochemistry showed that densities of α-SMA(+) and PECAM-1(+) cells in frontal cortex, striatum, and hippocampus were significantly increased following EE, suggesting the histological findings exhibit a similar pattern to the upregulation of FGF-2 in the brain. In conclusion, EE enhances endogenous angiogenesis and neurobehavioral functions mediated by upregulation of FGF-2 in chronic hypoxic-ischemic brain injury.
authors.affiliation: Department and Research Institute of Rehabilitation Medicine, Yonsei University College of Medicine, Seoul, Korea ; Graduate Program of Nano Science and Technology, Yonsei University, Seoul, Korea.
authors.forename: Jung Hwa
authors.initials: JH
authors.lastname: Seo
authors.forename: Ji Hea
authors.initials: JH
authors.lastname: Yu
authors.forename: Hwal
authors.initials: H
authors.lastname: Suh
authors.forename: Myung-Sun
authors.initials: MS
authors.lastname: Kim
authors.forename: Sung-Rae
authors.initials: SR
authors.lastname: Cho
mesh_terms: D000199:Actins / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D017931:DNA Primers / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006799:Housing, Animal; D020925:Hypoxia-Ischemia, Brain / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D053580:Muscle Strength / Q000502:physiology; D018919:Neovascularization, Physiologic / Q000502:physiology*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D045442:Rotarod Performance Test
chemical_list: D000199:Actins; D017931:DNA Primers; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C544013:alpha-smooth muscle actin, mouse; D016222:Fibroblast Growth Factor 2